1. Technical Field
The present disclosure relates to compositions and formulations containing microparticles and to methods of processing such compositions and formulations.
2. Description of Related Technology
Microparticles, microspheres, and microcapsules, referred to herein collectively as “microparticles,” are solid or semi-solid particles having a diameter of less than one millimeter, more preferably less than 100 microns, which can be formed of a variety of materials, including but not limited to various polymers and proteins. Microparticles have been used in many different applications, primarily separations, diagnostics, and drug delivery.
The most well known examples of microparticles used in separations techniques are those which are formed of polymers of either synthetic or protein origin, such as polyacrylamide, hydroxyapatite, or agarose. These polymeric microparticles are commonly used to separate molecules such as proteins based on molecular weight and/or ionic charge, or by interaction with molecules chemically coupled to the microparticles.
In the diagnostic area, spherical beads or particles have been commercially available as a tool for biochemists for many years. For example, microparticles have been derivatized with an enzyme, a substrate for an enzyme, or a labeled antibody, and then interacted with a molecule to be detected, either directly or indirectly. A number of derivatized beads are commercially available, all with various constituents and sizes.
In the controlled drug delivery area, molecules have been encapsulated within microparticles or incorporated into a matrix, to provide controlled release of the molecules. A number of different techniques have been used to make such microparticles from various polymers including phase separation, solvent evaporation, emulsification, and spray drying. Generally, the polymers form the supporting structure of the microspheres, and the drug or molecule of interest is incorporated into the supporting structure. Exemplary polymers used for the formation of microspheres include homopolymers and copolymers of lactic acid and glycolic acid (PLGA), block copolymers, and polyphosphazenes.